## Calculus with Applications (10th Edition)

a) $8.8\%$ b) $8.75\%$
In the formula for compound interest with let $P=\$10.500t=12A=\$30.000$ a) $m=4$ $A=P(1+\frac{r}{m})^{tm}$ $30000=10500(1+\frac{r}{4})^{12(4)}$ $(1+\frac{r}{4})^{48}=\frac{20}{7}$ $r\approx0.088\approx 8.8\%$ b) $A=Pe^{rt}$ $30000=10500e^{12r}$ $e^{12r}=\frac{20}{7}$ $r \approx 0.0875 = 8.75\%$